Author: Andrew Robert Nicols
MDL-20306 Add course_category idnumber field
http://git.moodle.org/gw?p=moodle.git;a=commit;h=83cd9b163a9d84a802d98073fac55fd4de0c184e
http://github.com/moodle/moodle/commit/83cd9b163a9d84a802d98073fac55fd4de0c184e
+ 2.2 en [idnumbercoursecategory,core]
+ 2.2 en [idnumbercoursecategory_help,core]